This proposal is to continue studies of the epidemiology, including gene-environment interaction, in the etiology of non-insulin-dependent diabetes mellitus (NIDDM), its complications, associated conditions such as the Metabolic Syndrome, and the potential for their prevention. The emergence of NIDDM and cardiovascular disease (CVD) in Pacific and Indian Ocean Islanders, and in these and other ethnic minorities in the U.S.A., has been concomitant with rapid socioeconomic and environmental changes, and differences exist in genetic susceptibility to NIDDM between ethnic groups. The investigators propose to continue to pursue objectives involving longitudinal studies in African-origin Creoles and to further analyze data collected over the past 20 years. Additional objectives include the evaluation of intervention activities aimed at reducing the incidence of NIDDM and CVD in Mauritius. The longitudinal studies will focus on the island communities of Mauritius, Nauru, and Western Samoa. Specifically, the research will aim to: 1) continue to monitor trends in the prevalence, incidence rate and natural history of impaired glucose tolerance (IGT) and NIDDM in Mauritius, Nauru, and W Samoa; 2) assess the behavioral, environmental and molecular/biochemical determinants of IGT and NIDDM in these populations, including hyperinsulinemia, obesity, fat distribution, physical activity, and diet; 3) define the determinants of micro- and macro-vascular complications of NIDDM, their associated morbidity and mortality, and assess their prevalence and incidence rates in relation to ethnic differences; 4) pursue questions regarding the current classification and diagnostic criteria for diabetes to improve treatment regimens, to more precisely define the epidemiology of diabetes and its risk factors, and to correctly identify individuals for lifestyle interventions; 5) evaluate strategies for primary prevention of NIDDM and other CVD risk factors, as well as secondary and tertiary prevention of diabetes complications; 6) investigate the extent and biological importance of the Metabolic Syndrome (CVD risk factor cluster) and the role of hyperinsulinemia/insulin resistance in the etiology of both the syndrome and CVD; and 7) evaluate whether leptin, the 'ob' gene product, plays a role in the etiology of obesity, NIDDM and insulin resistance. The investigators state that the proposed research has important implications for the U.S.A. because of the increasing migration of Pacific Islanders and Asians into the U.S. They further state the data are relevant to other high risk groups such as Native and African Americans, since NIDDM and its complications are potentially preventable. They point out that a greater understanding of environmental/behavioral determinants would provide important directions for developing primary prevention programs not only for NIDDM but also associated CVD in the U.S.A. and other countries.